Endoscopic instruments have been developed to provide surgeons with an internal view of the organ or body passage requiring treatment. Such endoscopes typically have channels through which flexible instruments, such as a miniaturized forceps, are inserted and advanced. The endoscope assembly includes an elongated flexible cable equipped at one end with an eyepiece or other viewing means and at the other end with an imaging means. The cable transmits images or image-producing signals from the illuminated operative site to the viewing means so that the surgeon will have visual confirmation of the action of the instrument's working end. The cable also provides a flow passage for the delivery of fluid (liquid or gas) for irrigation, insufflation, rinsing, or other purposes. For instance, it may be necessary to provide the optic head with a flow of sterile water. The passage of the sterile water across the optic head prevents the buildup of materials on the imaging means. This flow of water operates, in a sense, like a windshield wiper/washer assembly.
In normal practice, the endoscopic instrument has a control body which provides several ports that allow connectors to be attached for irrigation, insufflation, rinsing, or other purposes. These ports may include a variety of fittings that are suitable for various purposes. For example, air and water ports can receive an air/water connector suitable for providing air and/or water for rinsing and other purposes. As such, the air and water are delivered through the connector into the light guide connector or control body of the endoscope. The light guide connector or the control body can also include an irrigation port so as to allow irrigation water to be directly provided to the endoscope. Suitable valves are provided on the control body so as to control the flow of water and/or air through the control body and the flexible cable of the endoscope.
Unfortunately, there is usually a great expense associated with maintaining sterility of the equipment and/or water. Sterile water can be provided for rinsing from a water bottle that is connected to the endoscopic instrument via tubing. The tubing has a fitting at one end so as to allow the tube to be connected to the air/water port of the endoscopic instrument, and the other end of the tubing is inserted into the water bottle. Typically, the fitting will include two tubes, one providing water and the other providing air. Sometimes the two tubes may be concentric with an inner tube providing water and an outer tube providing air. The inner tube extends through a cap into the water bottle, and the outer tube is connected to the cap of the water bottle. Air may be delivered through the area between the inner tube and the outer tube so as to pressurize the interior of the water container. In some embodiments, the gas that pressurizes the bottle and insufflates the lumen may be supplied through a separate tube that interfaces with the bottle cap; in such a system, the gas flows from the bottle to the endoscope through the space between the inner tube and the outer tube. This will force water to flow through the tube and into the endoscope at a desired rate. For example, inner and outer tube sets that are utilized with endoscopes are described in U.S. Pat. Nos. 6,210,322 and 6,485,412, the contents of which are hereby incorporated by reference (see, e.g., '322 patent at Col. 3, 1. 42-Col. 4, 1. 6 and '412 patent at Col. 4, II. 34-48).
The purpose of irrigation is to clear debris from the field of view. When debris such as digestive waste, mucous, blood, and detached tissue cover portions of the lumen wall, the operator may be unable to make a proper assessment of the condition of the tissue or perform actions such as biopsy removal or cautery. When irrigation is desired, the endoscopic instrument can be connected to another water bottle using another set of tubing. One end of an irrigation tube is connected to an irrigation port of the endoscopic instrument, and the other end of the tubing extends through a cap so that it may be placed in a water bottle. The irrigation tube may provide a section of flexible tubing that is insertable into a peristaltic pump. The peristaltic pump provides water flow to the endoscope that is suitable for irrigation. The irrigation system moves water by drawing it out of the bottle with a peristaltic pump, so it requires a vent to allow air to enter the bottle. In contrast, the insufflation and lens rinsing system moves water by pushing it out of the bottle with internal pressure, so the tubing and bottle assembly must be sealed to maintain the pressure.
After usage, the two water bottles, the tubing, and the associated fittings are sterilized or disinfected if they are not disposable items. In the case that the items are disposable, two water bottles, tubing, and associated fittings are discarded. If the items are sterilized or disinfected, there is a considerable labor expense associated with cleaning, and disinfecting or autoclaving. Additionally, there is also the possibility of residual contaminants residing in the area of connection between the tubes and the bottle. This creates a considerable expense to the hospital in either case. In some systems, two bottles are required when the user desires to perform both functions because the designs of these systems treat them as separate and independent, individual systems.
Research has demonstrated that there is a clinical benefit when insufflation is performed using warm (e.g. body temperature) water instead of dry room temperature air. It is expected that this benefit is due to the fact that the warm water is more similar to the natural surroundings of the internal tissue than the cool, dry air. The sudden loss of temperature caused by insertion of air can make the muscles in the lining of the lumen contract and affect blood flow to the tissue. Also, when warm water is used for insufflation, the debris remaining on the tissue is readily washed away, which improves visibility for cancer screening when the user removes the water and adds air for insufflation. Warm water infusion typically is performed as the endoscope is inserted into the patient. The water is subsequently removed and replaced with air as the endoscope is being removed and the operator is looking for problematic tissues (such as cancerous tumors).
Just as the tissue is most commonly subjected to warm liquids than cool dry air, the gas that does pass through the digestive tract tends to be warm and humid. Thus it is advantageous to use warm, humid air whenever insufflation is performed with air. In some systems, the gas that enters the endoscope for insufflation first passes through the water bottle and then into the endoscope. In such a system, it is possible to warm the gas prior to it entering the bottle and/or warm the water in the bottle. If the gas is then forced to enter the bottle at the bottom and bubble to the top, it absorbs water and heat then leaves the bottle warm and humid as it travels to the endoscope for insufflation. A clinical benefit is expected as the gas is less likely to dry or cool the tissues, thus reducing cramping of the luminal wall. If the gas used for this procedure is carbon dioxide instead of atmospheric air, the carbon dioxide absorbs into the tissues more than 100 times faster. The absorption rate of carbon dioxide into digestive tissues is 100 to 150 times that of oxygen and nitrogen, which combine to make up about 99% of atmospheric air. Because carbon dioxide is absorbed into the tissues and expired through the respiratory system, the gas in the lumen does not have to pass through the remainder of the digestive system, thus improving patient discomfort and speeding recovery. The lens rinsing system, similar to the irrigation system, comprises a continuous liquid path interrupted only by valves. (The irrigation system fluid path also is interrupted by the pump rollers.) It is desirable to maintain sterility of the water in the water bottle that serves a source of water for lens rinsing. Thus, it is desirable to add a check valve in the lens rinsing flow path. This check valve is preferably incorporated in the air/water connector of the tube set since the valve can then be disposed of with the tube set rather than being reprocessed with the endoscope. The check valve can help to prevent cross-contamination.